System and method for the hybrid construction of multi-piece parts

ABSTRACT

A multi-piece part includes multiple pieces fabricated via different types of fabrication processes, wherein the multiple parts are configured to be coupled to one another to form the assembly. At least one of the multiple parts is fabricated via an additive manufacturing method. The multi-piece part also includes a holder assembly that couples and holds together the multiple pieces of the multi-piece part, wherein the holder assembly comprises a reversible, mechanical-type coupling.

BACKGROUND

The subject matter disclosed herein relates generally to gas turbines,and, more particularly to fabrication of multi-piece parts (e.g.,nozzles) for gas turbine systems.

A gas turbine system combusts a fuel to generate hot combustion gases,which flow through a turbine to drive a load and/or a compressor. Insuch systems, fabrication of parts (e.g., nozzle segments, blades,shrouds, etc.) may be complex at least due to different desiredmechanical and physical properties and/or complex geometries andfeatures of the parts. It may be challenging to construct parts to meetthe design goals and targets on multiple fronts. For example, it may bedesirable for parts that are subjected to the high temperatures in a hotgas path of a gas turbine system to have particular mechanical and/orthermal properties that are challenging to achieve with asingle-material fabrication process. These parts may also include fine(e.g., small) cooling features that can be challenging or impossible tomanufacture using typical manufacturing methods, such as casting.Further, even when certain relatively fine features can be constructedusing typical manufacturing methods, such as casting, these processestypically suffer in terms of production time, high defects rates, andlow yields.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In one embodiment, a multi-piece part includes multiple piecesfabricated via different types of fabrication processes, wherein themultiple parts are configured to be coupled to one another to form theassembly. At least one of the multiple parts is fabricated via anadditive manufacturing method. The multi-piece part also includes aholder assembly that couples and holds together the multiple pieces ofthe multi-piece part, wherein the holder assembly comprises areversible, mechanical-type coupling.

In another embodiment, a multi-piece turbine part includes a first piecefabricated via an additive manufacturing process, and a second piece anda third piece fabricated via a casting process. The multi-piece turbinepart includes alignment features on a first interface between the firstsegment and the second segment and on a second interface between thefirst segment and the third segment, wherein the first segment iscoupled to the second segment at the first interface and the firstsegment is coupled to the third segment at the second interface. Themulti-piece turbine part also includes a holder assembly that extendsthrough and couples together the first piece, the second segment, andthe third segment of the multi-piece turbine part.

In another embodiment, a method includes fabricating a plurality ofpieces of a multi-piece part via a plurality of different types offabrication processes. At least one of the plurality of pieces isfabricated via an additive manufacturing process. The method includescoupling the plurality of pieces together to assemble the multi-piecepart. The method also includes securing the assembled plurality ofpieces of the multi-piece part together via a holder assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a gas turbine system, in accordance withembodiments of the present disclosure;

FIG. 2 is a partial side cross-sectional view of a portion of the gasturbine system of FIG. 1, in accordance with embodiments of the presentdisclosure;

FIG. 3 is a flow chart illustrating a process for fabricating amulti-piece part of the gas turbine system of FIG. 1 via a multi-piecehybrid fabrication process, in accordance with embodiments of thepresent disclosure;

FIG. 4 is a perspective view of a multi-piece part, namely a stage onenozzle segment of the gas turbine system of FIG. 1, which may befabricated via the multi-piece hybrid fabrication process of FIG. 3, inaccordance with embodiments of the present disclosure; and

FIG. 5 is a cross-sectional view of a portion of the nozzle segment ofFIG. 4 taken along a line 5-5, in accordance with embodiments of thepresent disclosure; and

FIG. 6 is an exploded view of the nozzle segment of FIG. 4, inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

As set forth above, there is currently a need for an improved approachon fabrication of complex parts, especially for complex parts withnumerous physical and mechanical target properties. Conventionally,these parts are manufactured using single (e.g., all-at-once)fabrication method. For example, certain turbine parts are presentlymanufactured using a casting process, in which a single material, whichis usually a metal or alloy, is introduced into a mold in a molten stateand subsequently solidifies to take the shape of the mold. However, suchmonolithic fabrication techniques can introduce various limitations withrespect to material selection, manufacturing process freedom, and/or theability to implement fine features.

With this in mind, present embodiments are directed to a multi-piecehybrid fabrication of a part (e.g., a turbomachine part) via differentprocesses (e.g., casting, molding, and additive manufacturing, etc.)and/or using multiple materials (e.g., ceramics, metals, alloys,composites, etc.). For example, as discussed in greater detail below, amulti-piece stage one nozzle segment, including a central vane piece(e.g., an airfoil) and two endwall pieces (e.g., outer and inner bandsegments), may be constructed by first fabricating and then assemblingthe individual pieces of the part. Accordingly, each piece of the stageone nozzle segment may be manufactured separately using differentmanufacturing methods and/or using different materials that are bettersuited for the respective pieces. For example, the endwalls may befabricated via casting, while the vane may be fabricated via an additivemanufacturing process (e.g., direct metal melting, direct metalsintering, binder jetting, etc.) that is more suitable for fabricatingfine features, such as small cooling channels within the wall of theairfoil. The individual pieces (e.g., the vane and the endwalls) arethen assembled together to form the part (e.g., the stage one nozzlesegment). In addition, because the part is assembled via multiplepieces, each piece may be post processed separately (e.g., via heattreatments, surface treatments, surface coatings, etc.), machinedseparately (e.g., to make cooling holes among other features), inspectedseparately, and/or repaired or replaced separately. As such, presentembodiments enable greater freedom (e.g., few restrictions) on thefabrication process to enable advanced designs via different processesand/or using multiple materials.

FIG. 1 is a block diagram of an embodiment of a gas turbine system 10,which may include features (e.g., cooling features such as coolingchannels, cooling holes, impingement sleeves, flow guides, etc.) toimprove cooling within certain portions of the system 10. Asappreciated, the systems and methods described herein may be used in anyturbine system, such as gas turbine systems and steam turbine systems,and is not intended to be limited to any particular machine or system.As shown, the system 10 includes a compressor 12, a turbine combustor14, and a turbine 16, wherein the turbine 16 may include one or moreseparate stages 18. The system 10 may include one or more combustors 14that include one or more fuel nozzles 20 configured to receive a liquidfuel and/or gas fuel 22, such as natural gas or syngas.

The turbine combustors 14 ignite and combust a fuel-air mixture, andthen pass hot pressurized combustion gases 24 (e.g., exhaust) into theturbine 16. Turbine blades are coupled to a shaft 26, which is alsocoupled to several other components throughout the gas turbine system10. As the combustion gases 24 pass through the turbine blades in theturbine 16, the turbine 16 is driven into rotation, which causes theshaft 26 to rotate. Eventually, the combustion gases 24 exit the gasturbine system 10 via an exhaust outlet 28. Further, the shaft 26 may becoupled to a load 30, which is powered via rotation of the shaft 26. Forexample, the load 30 may be any suitable devices that may generate powervia the rotational output of the gas turbine system 10, such as anelectrical generator, a propeller of an airplane, and so forth.

Compressor blades may be included as components of the compressor 12.The blades within the compressor 12 are coupled to the shaft 26, andwill rotate as the shaft 26 is driven to rotate by the turbine 16, asdescribed above. An intake 32 feeds air 34 into the compressor 12, andthe rotation of the blades within the compressor 12 compresses the air34 to generate pressurized air 36. The pressurized air 36 is then fedinto the fuel nozzles 20 of the turbine combustors 14. The fuel nozzles20 mix the pressurized air 36 and fuel 22 to produce a suitable mixtureratio for combustion.

FIG. 2 is a partial cross-sectional side view of an embodiment of thegas turbine system 10. As shown, the gas turbine system 10 may bedescribed with reference to a longitudinal axis or direction 38, aradial axis or direction 40, and a circumferential axis or direction 42.The hot combustion gases 24 may flow from the combustors 14 (FIG. 1)into the turbine 16 in a direction generally along the longitudinal axis38, illustrated by an arrow 44 in FIG. 2. Each of the stages 18 of theturbine 16 includes a set of blades 46 coupled to a rotor wheel that maybe rotatably attached to the shaft 26. The turbine 16 includes turbinenozzle segments 48 within each of the stages 18, and the turbine nozzlesegments 48 direct the hot combustion gases 24 towards the set of blades46 of the respective stage 18. The turbine nozzle segments 48 describedherein may be employed in a first stage, second stage, third stage, orcombinations thereof, wherein “first” refers to the stage immediatelydownstream of the combustor 14. As may be appreciated, the term“downstream” generally refers to the direction of the combustion gases24 through the turbine 16 along the longitudinal axis 38, as shown bythe arrow 44. Likewise, the term “upstream” generally refers to theopposite direction (e.g., towards the compressor 12) along thelongitudinal axis 38.

Each nozzle segment 48 may include circumferentially spaced vanes 50(e.g., each defining an airfoil) that extend in the radial direction 40between band segments 52 and 54 (e.g., inner and outer band segments).The adjacent band segments 54 (e.g., outer band segments) may be coupledtogether to form an outer annular ring extending around an inner annularring of the adjacent band segments 52 (e.g., inner band segments). Thevanes 50 may extend between the two annular rings formed by the bandsegments 52 and 54 (e.g., inner and outer band segments). The gasturbine system 10 may also include shroud segments 56, which may bedisposed downstream of the band segments 54 (e.g., outer band segments)to direct hot combustion gases 24 flowing past the vanes 50 to theblades 46. Structures or components disposed along the flow path of ahot gas (e.g., the combustion gases 24) may be referred to as heatedstructures or components. In one example, the heated structure may bethe blades 46 and other parts (e.g., vanes 50) of the turbine nozzlesegment 48. In some embodiments, to cool the heated structures (e.g.,vanes 50), cooling features, such as impingement sleeves, coolingchannels, cooling holes, etc. may be disposed within the heatedstructures, as indicated by the dashed line 78. For example, cooling airas indicated by an arrow 79 may be routed from the compressor 12 orelsewhere and directed through the cooling features as indicated byarrows 81.

Present embodiments are directed to the multi-piece hybrid fabricationof a part via different processes (e.g., casting, molding, and additivemanufacturing, among others) and/or using multiple materials (e.g.,ceramics, metals, alloys, composites, etc.). It may be appreciated thatthe disclosed multi-piece hybrid fabrication process may be used tofabricate any suitable parts or segments of the gas turbine system 10.By way of a non-limiting example, the multi-piece hybrid fabricationprocess may be used to fabricate a stage one nozzle segment, asmentioned above and discussed in greater detail below. The disclosedmulti-piece hybrid fabrication process may also be used to fabricate anysuitable multi-piece parts (e.g., parts used in automobile industry,aeronautical industry, medical industry, gas and mining industry,sporting goods, tools and equipment, etc.).

FIG. 3 is a flow chart illustrating an example of a multi-piece hybridfabrication process 100 for fabricating a multi-piece part, inaccordance with embodiments of the present technique. In the illustratedembodiment, the process 100 generally includes fabricating the pieces ofthe part (block 102) and post-processing the pieces of the part (block104) before the pieces of the part are assembled (block 106). In certainembodiments, depending on issues encountered during manufacturing, theprocess 100 may include a disassembling (block 108) the pieces of thepart, post-processing (block 104) or repairing (110) one or more piecesof the part, and then reassembling the piece of the part (block 106).

As illustrated, fabricating the pieces of the part (block 102) caninvolve multiple individual manufacturing or fabrication techniques. Forexample, in certain embodiments, the fabrication techniques may includefabricating pieces via casting (block 120), fabricating pieces viaadditive manufacturing (block 122), fabricating pieces via molding(block 124), and/or fabricating pieces via other suitable methods orprocesses (block 126). It may be appreciated that the part (e.g., thefinal, assembled product) generally includes multiple pieces or segmentsthat are later assembled. Since different fabrication processes may beemployed, the pieces may be made of different materials, resulting in amulti-piece part having combinations of materials (e.g., differentalloys, metals and ceramics) not possible using conventionalmanufacturing techniques. The pieces may have different shapes orfeatures varying in complexity from one another, and the presenttechnique enables the use of finer resolution manufacturing techniques(e.g., additive manufacturing) for intricate pieces of a part, whileusing faster and/or lower cost manufacturing techniques for pieces ofthe part that have less complex geometries. As such, the various piecesof the part can be fabricated via suitable processes selected from thelisted fabrication processes (e.g., processes 120, 122, 124, and 126) inaccordance with the desired properties and the complexity of each piece.

The fabrication process represented by block 120 may include anysuitable casting process, in which a piece of the part may be formedfrom materials suitable for casting (e.g., metal or metal alloys). Forexample, in certain embodiments, the fabrication process 120 may includea variety of casting processes, such as centrifugal casting, diecasting, glass casting, investment casting, lost-foam casting, lost-waxcasting, permanent mold casting, rapid casting, sand casting,slipcasting, among other casting processes. In certain embodiments, themetal or alloy may be introduced into the mold in molten form (e.g., asa liquid) or as a slurry that includes metallic particles. In the lattercase, the metallic particles may be subsequently sintered to solidifythe piece of the part within the mold, and the mold removed to yield thepiece of the part. In certain embodiments, the casting process made beused to form a single-crystal part. In certain embodiments, the castedpart may be directionally solidified or equiaxed.

The fabrication process represented by block 122 may include anysuitable additive manufacturing processes, in which a piece of the partmay be formed from materials suitable for additive manufacturing, suchas metals, polymers, ceramic, or a combination thereof. The fabricationprocess 122 may include a variety of additive manufacturing processes,such as material jetting, binder jetting or binderjet process, materialextrusion, powder bed fusion, sheet lamination, directed energydeposition, three-dimensional (3D) printing, direct metal laser melting(DMLM), direct metal laser sintering (DMLS), electron beam meltingprocess, among other additive manufacturing processes.

It may be appreciated that the additive manufacturing processesrepresented by block 122 may be used to fabricate pieces of the partthat include fine features (e.g., small and/or complex features, such ascooling channels, cooling holes, flow guides, etc.) that may bedifficult or impossible to fabricate via other methods. In addition,because a wide variety of materials may be used in additivemanufacturing, this enables greater freedom in material options forconstructing the part. For example, in certain embodiments, DMLM andDMLS may be used to fabricate pieces of the part that are better suitedto be made of metal or metal alloys. By further example, in certainembodiments, a binderjet process may be used to fabricate pieces thatare better suited to be made of high-strength materials and/ordispersion strengthened materials, such as nickel and cobalt basedsuperalloys. In certain embodiments, these materials may include ceramicand/or intermetallic materials, such as aluminides (e.g., nickelaluminide, titanium aluminide), silicides (e.g., titanium silicide,niobium silicide), metal matrix composites, ceramic matrix composites,ceramic matrix having reinforcement materials, such as silicon carbide,boron nitrides, fibers, nanotubes, among other high strength materials.

The fabrication process indicated by block 124 may include any suitablemolding processes, in which a piece of the part may be formed frommaterials suitable for molding. For example, in certain embodiments, thefabrication process 124 may include a variety of molding processes, suchas, blow molding, compression molding, extrusion molding, injectionmolding, thermoforming, among other molding processes. The fabricationprocess 126 may include other suitable processes (e.g., milling,stamping) not-listed above that may be used to fabricate pieces of thepart. As such, each piece of the part may be separately fabricated via asuitable process considering factors including, but not limited to,desired material properties (e.g., mechanical properties, thermalproperties, electrical properties, etc.), geometries, sizes, dimensions,shapes, costs, fabrication efficiency, fabrication speed, etc.

Upon completion of the fabrication of pieces in block 102, some or allof the pieces may be subjected to one or more post-processing steps 104before the part is assembled. Alternatively, in certain embodiments,post-processing 104 may be omitted. In certain embodiments,post-processing 104 may include a heat treating pieces (block 140),machining pieces to modify pieces (block 142), applying one or moresurface coatings to pieces (block 144), and/or to inspecting pieces(block 146). The freedom to post-process individual pieces offers manyadvantages. For example, different post-processing treatments and/orinspection may be efficiently applied to the targeted pieces withoutinterventions or complications from the pieces that may not need suchtreatment(s) and/or inspection(s). Moreover, any identified defects maybe addressed or the piece of the part may be swapped for a non-defectivepiece, without affecting the other pieces of the part or affectingoverall part yield.

Upon completion of post-processing the pieces of the part in block 104,the pieces may be assembled (block 106) to form the part, as discussedbelow in greater detail with respect to FIG. 6. The assembly of block106 may include one or more steps to removably couple (e.g.,mechanically couple) and/or fixedly couple (e.g., weld or braze)together the pieces that form the part.

In some embodiments, the illustrated process 100 for fabricating themulti-piece part may also include steps for repairing or remanufacturinga part, for example, that is damaged or worn during use or installation,or that is damaged during manufacturing. For example, in certainembodiments, the process 100 includes disassembling the pieces of thepart 108, repairing (block 110) the pieces, followed by the re-assemblyof the part (block 106). For example, upon determination that a piece ofthe part is damaged or defective, the individual pieces of the part maybe disassembled to enable easy access for repair or replacement of theparticular piece. Upon completion of the repair or replacement, thepieces may be reassembled (e.g., the process 106) to form the part. Insome embodiments, upon determining that pieces of the part are due forservicing, the pieces of the part may be disassembled (block 108), andone or more pieces may receive post-processing 104 (e.g., heat treating,machining, surface coating, and/or inspecting), in addition oralternative to the repairing described in block 110. Upon completion ofthe post-processing 104 and/or repair 110, the pieces may be reassembled(e.g., the process 106) to form the part.

By way of non-limiting example, FIG. 4 illustrates an example of a part170 that may be fabricated using the multi-piece hybrid fabricationprocess (e.g., process 100) set forth above. FIG. 4 shows a perspectiveview of an example of a part 170 that includes a first piece 172, asecond piece 174, and a third piece 176. In the illustrated embodiment,the part 170 is a nozzle segment 170 (e.g., first stage nozzle) thatincludes a vane 172, endwall 174 (e.g., corresponding to the outer bandsegment 54 in FIG. 2), and endwall 176 (e.g., corresponding to the innerband segment 52 in FIG. 2). The vane 172 generally has an airfoil shapeextending between a first end 178 and a second end 180, and between aleading edge 182 and a trailing edge 184. The vane 172 is configured tobe coupled between the end walls 174 and 176 to form the nozzle segment170, as will be discussed in FIG. 6.

The endwall 174 may include one or more openings 175 that extend betweena first side 186 and a second side 187, as well as coupling features 188(e.g., female connectors or openings) disposed on the first side 186.The endwall 176 may include one or more openings 177 that extend betweena first side 190 and a second side 191, as well as coupling features 192disposed on the first side 190. The coupling features 188 and 192 may beconfigured to interface with corresponding features (e.g., alignmentfeatures 194) disposed on the respective first end 178 and the secondend 180 of the vane 172. For example, in certain embodiments, thecoupling features 188 and 192 may include, but are not limited to,snap-fit features, friction-fit features, interference-fit features,form-fit features. For example, in certain embodiments, the couplingfeatures 188 and 192 may each include a raised portion with respect tothe first sides 186 and 190, respectively, and the raised portion mayhave a periphery or outline that matches the periphery or outline of therespective first end 178 and the respective second end 180,respectively. For example, in certain embodiments, these peripheries oroutlines have the shape of an air foil, a tear drop, or an ear.

As mentioned, the illustrated vane 172 includes alignment features 194(e.g., male connectors or pillars) on the first end 178 and on thesecond end 180 that correspond with and are inserted into the couplingfeatures 186 and 190 during assembly. For example, as illustrated, thealignment features 194 may include one or more protrusions, and thecoupling features 196 and 198 disposed on the coupling features 188 and190 (e.g., disposed on the raised portions) may include one or morerecesses configured to receive the protrusions (e.g., alignment features194). As such, these alignment features 194 and the coupling features196 and 198 may assist alignment and/or coupling between the vane 172and the endwalls 174 and 176. It may be appreciated that, in otherembodiments, the alignment features 194 and the coupling features 196and 198 may include other suitable features.

The vane 172 may include one or more cooling features, such as coolingchannels 200. In the illustrated embodiment, the cooling channels 200may extend within a wall or shell 202 of the vane 172 between theleading edge 182 the trailing edge 184. For example, FIG. 5 illustratesa cross-sectional view of the vane 172 of FIG. 4 taken along the line5-5. As such, FIG. 5 illustrates that the cooling channels 200 may bedisposed within the wall 202 at distance or spacing 204 from oneanother. The spacing 204 may be constant or may vary between each pairor adjacent cooling channels 200. The cooling channels 200 may each havea feature size 206 (e.g., width, diameter). In some embodiments, thefeature size 206 may be between about 0.3 millimeter and about 3millimeters. The feature size 206 may be constant or may vary for eachcooling channels 200. In some embodiments, the vane 172 may includeother cooling features and/or flow guiding features that may have finedimensions and/or complex shapes.

It may be appreciated that at least due to the fine dimensions and/orthe distribution of the cooling channels 200, it may be more suitableusing certain processes to fabricate the vane 172. For example, it maybe challenging to fabricate these cooling channels 200 via casting(block 120) and easier or more suitable to fabricate these via anadditive manufacturing process (block 122). Further, because the nozzlesegment 170 may be disposed along the hot gas path, it may be desirablefor at least a portion of the nozzle segment 170 to be made of materialsof high mechanical strength, such as ceramic and/or intermetallicmaterials (e.g., aluminides, silicides, metal matrix composites, ceramicmatrix composites, ceramic matrix having reinforcement materials, etc.).As such, in certain embodiments, the vane 172 of the nozzle segment 170may be fabricated via binderjet process to enable a variety of materialchoices. In some embodiments, the endwall 174, and the endwall 176 maybe fabricated via casting (e.g., the process 120). In some embodiments,the endwalls 174 and 176 may be fabricated using a different materialthan that used to fabricate the vane 172. For example, in certainembodiments, the endwalls 174 and 176 may be made of metal or metalalloys, while the vane 172 may be made of ceramic and/or intermetallicmaterials. As such, the nozzle segment 170 may be fabricated viadifferent processes and/or via different materials for differentindividual pieces.

FIG. 6 illustrates an exploded view of an example nozzle segment 220that includes the vane 172 and the endwalls 174 and 176, as illustratedin FIG. 4, as well as a holder assembly 222 that to holds the assemblednozzle segment 170 together. In the illustrated embodiment, the holderassembly 222 includes a mechanical type coupling including athrough-bolt 224, a first nut 226, a second nut 228, a first crossmember230, and a second crossmember 232. The illustrated endwall 174 includesa space or cavity 234 on a second side 187, and the crossmember 230 issized to be received in the space 234 (e.g., via male-female fit, formfit, etc.). For example, the crossmember 230 may have a plate-like shapewith a thickness 236, a first side 238, and a second side 240. In someembodiments, the thickness 236 may be smaller than a depth 242 of thespace 234, and the shape or dimensions of the crossmember 230 are suchthat the crossmember 230 may fit into the space 234 and completely coverthe one or more openings 175 of the endwall 174. In some embodiments,the first side 238 may include features that may form fit or form amale-female coupling with features on the second side 187 of the endwall174.

Likewise, the endwall 176 may include a space or cavity 250 on thesecond side 191, and the crossmember 232 may be configured to bereceived in the space 250 (e.g., via male-female fit, form fit, etc.).For example, the crossmember 232 may have a thickness 252, a first side254, and a second side 256. In some embodiments, the thickness 252 maybe smaller than a depth 258 of the space 250, and the shape ordimensions of the crossmember 232 are such that the crossmember 232 mayfit into the space 250 and completely cover the one or more openings 177of the endwall 176. In some embodiments, the first side 254 may includefeatures that may form fit or form a male-female fit with features onthe second coupling side 191 of the band segment 176.

Further, the crossmember 230 and the crossmember 232 each has an openingor a hole 260 that extends between the respective first and secondsides. When the vane 174 and the endwalls 174 and 176 are coupled to oneanother, the holes 260 are aligned with at least one of the one or moreopenings 175 and 177, such that the through-bolt 224 may extend along anaxis 262 (e.g., radial axis 262) through a retention feature 226 (e.g.,nut 226), through the hole 260 on the crossmember 230, through the oneor more openings 175 and 177 in the vane 172, through the hole 260 onthe crossmember 232, and through another retention feature (e.g., nut228). The through-bolt 224 and the retention features 226 and 228 may betightened to secure the coupling between the vane 172 and the endwalls174 and 176. In some embodiments, the holder assembly 222 may includeany number of through-bolts and any number of retention features. Insome embodiments, the holder assembly 222 may include any number ofcrossmembers. In some embodiments, the holder assembly 222 may includeany other mechanical types of coupling using nuts and bolts (e.g.,flange coupling, groove coupling, etc.).

In some embodiments, joints between one or more elements of theto-be-assembled nozzle segment 220 may be brazed, for example, duringpost-assembly processing of the multi-piece part. For example, a jointformed between the crossmember 230 and the endwall 174 (e.g., along thecircumference of the first side 238) and/or a joint formed between thecrossmember 232 and the endwall 176 (e.g., along the circumference ofthe first side 254) may be brazed to substantially reduce or eliminategas leakage (e.g., into the one or more openings 175 and 177). Byfurther example, joints formed between the tightened through-bolt 224and nuts 226 and 228 may be brazed to substantially reduce or eliminategas leakage.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

The invention claimed is:
 1. A multi-piece part, comprising: multiplepieces fabricated via different types of fabrication processes, whereinthe multiple pieces are configured to be coupled to one another to formthe multi-piece part, and wherein the multiple pieces comprise: a piecefabricated via an additive manufacturing process, wherein the pieceincludes cooling channels extending within a wall of the piece, whereinthe wall includes an end face; and an additional piece fabricated via acasting process, wherein the additional piece includes an additional endface, wherein complementary alignment features are formed on the endface and the additional end face, and wherein the piece is configured tocouple to the additional piece at an interface between the end face andthe additional end face such that the complementary alignment featuresreceive and engage one another along the interface; and a holderassembly that couples and holds together the multiple pieces of themulti-piece part, wherein the holder assembly comprises a reversible,mechanical-type coupling.
 2. The multi-piece part of claim 1, whereinthe additive manufacturing process comprises a binderjet process, athree-dimensional printing process, a direct metal laser meltingprocess, a direct metal laser sintering process, or an electron beammelting process.
 3. The multi-piece part of claim 1, wherein theadditional piece of the multiple pieces is a single crystal ordirectionally solidified or equiaxed.
 4. The multi-piece part of claim1, wherein the multi-piece part is a component of a turbine system. 5.The multi-piece part of claim 1, wherein the additional piece of themultiple pieces is made of a metallic material, and the piece of themultiple pieces is made of a metal matrix composite, a ceramic matrixcomposite, or an intermetallic material.
 6. The multi-piece part ofclaim 1, wherein each of the cooling channels has a width between 0.3millimeter and 3 millimeters.
 7. The multi-piece part of claim 1,wherein the complementary alignment features comprise male-femalefittings.
 8. The multi-piece part of claim 1, wherein a spacing betweenindividual cooling channels of the cooling channel varies along adimension of the wall.
 9. The multi-piece part of claim 1, wherein thepiece is fabricated via the additive manufacturing process such that thepiece includes a plurality of layers of material bonded to one another.10. The multi-piece part of claim 1, wherein the piece is a first pieceand the end face is a first end face, wherein the wall of the pieceincludes a second end face opposite the first end face, wherein theadditional piece is a second piece and the additional end face is athird end face, and wherein the multiple pieces further comprise a thirdpiece fabricated via a casting process and including a fourth end face,wherein additional complementary alignment features are formed on thesecond end face and the fourth end face, and wherein the first piece iscoupled to the third piece at an additional interface between the secondend face and the fourth end face such that the additional complementaryalignment features receive and engage one another along the additionalinterface.
 11. A multi-piece turbine part, comprising: a first segmentfabricated via an additive manufacturing process, wherein the firstsegment includes cooling channels extending within a wall of the firstsegment, wherein the wall includes a first end face and a second endface opposite the first end face; a second segment and a third segmentfabricated via a casting process, wherein the second segment includes athird end face and the third segment includes a fourth end face; a firstset of complementary alignment features formed on the first end face andthe third end face and a second set of complementary alignment featuresformed on the second end face and the fourth end face, wherein the firstsegment is coupled to the second segment at a first interface betweenthe first end face and the third end face such that the first set ofcomplementary alignment features receive and engage one another alongthe first interface, and wherein the first segment is coupled to thethird segment ata second interface between the second end face and thefourth end face such that the second set of complementary alignmentfeatures receive and engage one another along the second interface; anda holder assembly that extends through and couples together the firstsegment, the second segment, and the third segment of the multi-pieceturbine part.
 12. The multi-piece turbine part of claim 11, wherein themulti-piece turbine part is a first stage nozzle segment, the firstsegment is a vane having an airfoil shape, the second segment is anouter band segment, and the third segment is an inner band segment. 13.The multi-piece turbine part of claim 11, wherein the first set ofcomplementary alignment features and the second set of complementaryalignment features comprise protrusions and recesses to form male-femalefittings.
 14. The multi-piece turbine part of claim 11, wherein thefirst segment is made of a material different from the second segmentand the third segment.
 15. The multi-piece turbine part of claim 11,wherein the first set of complementary alignment features includes afirst plurality of alignment features configured to receive and engageone another along the first interface and the second set ofcomplementary alignment features includes a second plurality ofalignment features configured to receive and engage one another alongthe second interface.
 16. A multi-piece part, comprising: a first piecefabricated via an additive manufacturing process, wherein the firstpiece includes cooling channels extending within a wall of the firstpiece, wherein the wall includes a first end face and a second end faceopposite the first end face; a second piece and a third piece fabricatedvia an additional manufacturing process, wherein the second pieceincludes a third end face and the third piece includes a fourth endface; a first set of complementary alignment features formed on thefirst end face and the third end face, wherein the first piece iscoupled to the second piece along a first interface between the firstend face and the third end face such that the first set of complementaryalignment features receive and engage one another along the firstinterface; and a holder assembly that extends through and couplestogether the first piece, the second piece, and the third piece of themulti-piece part.
 17. The multi-piece part of claim 16, wherein theholder assembly comprises a reversible, mechanical-type coupling. 18.The multi-piece part of claim 17, wherein the additive manufacturingprocess comprises a binderjet process, a three-dimensional printingprocess, a direct metal laser melting process, or a direct metal lasersintering process.
 19. The multi-piece part of claim 18, wherein theadditional manufacturing process comprises a casting process.
 20. Themulti-piece part of claim 16, wherein the multi-piece part comprises asecond set of complementary alignment features formed on the second endface and the fourth end face, wherein the first piece is coupled to thethird piece along a second interface between the second end face and thefourth end face such that the second set of complementary alignmentfeatures receive and engage one another along the second interface.